This page contains a simple glossary of technical terms used in our content.
If clarification or further information is needed, feel free to contact us.

Word

Definition

Active mode

A term applied to electromagnetic locator surveying where a signal is directly connected or induced onto a pipe or cable. This term also includes the tracing of accessible pipes and ducts through the insertion of a radiosonde or line threader (see also ‘passive mode’)

Base mapping

Mapping often supplied by the client at an appropriate scale in vector format onto which the results of the survey can be overlaid

Cable

A line normally to conduct electricity and so contains metal which can be detected with an electromagnetic locator

CAD

Computer aided design often used to overlay the results of the survey onto base mapping

CAT & Genny

An acronym for a locator being a ‘cable avoidance tool’ and signal generator

Diffraction

A GPR term used to describe the ‘hyperbolic’ shape seen in a radargram caused by the reflections from a buried pipe

Drainage

A network of pipes and channels to collect both foul and surface water and carry it to an outfall

Duct

A pipe (normally relatively small diameter) installed to carry cables or other utilities

EM

Electromagnetic – the principle behind the operation of locators

EML

Electromagnetic locator

EOT

End of trace with a reason why. Other terms such as ‘unable to trace’ (UTT) or ‘signal lost’ (SL) are also used

EuroGPR

European GPR association

Excavation (hand)

A trial pit or trench temporarily dug by hand to expose utilities to confirm their position

Fibre optic

A telecommunication line using optical fibres for the transmission of data. Unless reinforced the line will not contain metal so is undetectable with an EM locator

Geophysics

The measurement of physical properties of the ground. Anomalies in the data can be used to determine the position and size of buried features

GPR

Ground penetrating radar

GPS

Global positioning system

Gravity systems

A drainage system that relies on gravity to convey the water. Access is therefore possible via manholes and can be traced with radiosondes or line tracers

Inspection chamber

A chamber affording access onto a utility – often too small to allow a person to enter

Line threading

The use of a rod or radiosonde that emits a signal allowing its route to be detected and traced at ground level

Main

The principal utility conveying liquid, gas, telecommunications or power as part of a distribution or collection system. This would normally lie beneath part of a highway

Manhole

An access onto a utility line large enough for man entry. Mainly associated with drainage systems

Overhead

Common usage describing the position of a utility if not buried

Passive mode

A term applied to electromagnetic locator surveying where passive signals emitted by a pipe (power and radio modes) are detected and traced on the ground (see also ‘active mode’)

Pipe

A conduit mainly used for gases and liquids. Can be made from metallic and non-metallic materials

Radargram

The output trace from a GPR unit along a transect. It is made up of a series of individual point scans to form an apparent continuous image

Radiosonde

A small self-contained device emitting a signal that can be inserted into a conduit and then traced at ground level

Scar

A scar on the ground surface indicating where a utility may have been buried. This is often in the form of road surface reinstatement

Service

The connection from a utility main to a property

Signal generator

A device used to generate an electromagnetic signal that can be induced or directly connected to a conductor

Survey (utility)

The process of carrying out the detection location and mapping of buried utilities

Survey area

The area defined by the client within which the survey is to be carried out

Trace

The detection of a signal associated with a utility. It is implied that the line is also marked onto the ground surface

Transect

A line or swept width along which a search is carried out – often associated with GPR surveys

Trench

A temporary hole dug to visually locate and measure the position of a utility

Underground

A term used to describe a buried utility as opposed to overhead

UTL/UTR

Unable to lift/unable to raise – usually referring to manhole covers etc. Some contractors may also use this to mean ‘unable to locate’, which refers to a lost or buried manhole cover.